The present invention relates to a polishing instrument for polishing a surface into a predetermined shape and, in particular, to a polishing instrument which can be suitably used for the sheet metal repair of a vehicle.
Regarding sheet metal repair for dealing with flaws, dents, etc. generated on a painted surface of a vehicle, such as an automobile, substrate preparing procedures will be briefly described. First, as shown in FIG. 12, a coating film removing processing is performed to remove coating films, such as a primer 51, a surfacer 52, and a paint 53, from a steel plate 50.
Further, simultaneously with or after the coating film removing processing, a process for removing feather edges F is performed as shown in FIG. 13. The process for removing feather edges F is for generating smooth inclined portions (inclined by approximately 27 to 54 degrees) which extend from the steel plate surface 50 of the damaged portion D to the normal painted surface. Note that, the process for removing feather edges F is performed in order to improve the adhesion (holding) of putty P, with which the damaged portion D is filled afterward, and to restrain the reduction in the volume of the putty P as it cures, thereby making it possible to obtain a putty filling surface which is as flat as possible. And, the dent of the damaged portion D from which the coating films and feather edges F have been removed is elicited by a sliding hammer or the like, and then the dent is filled with putty P to form a putty-filled portion constituting the substrate in the damaged portion D. Note that, in the following, the damaged portion D is also referred to as the surface to be polished.
Conventionally, in this substrate preparing process, a rotary polishing device S, such as a discs sander or a double action sander, is generally used. As shown in FIG. 14, such a rotary polishing device S has a rotation mechanism 101 using compressed air or electricity as its power source, and a round polishing instrument 104 having a polishing paper 103 on the front side is detachably attached to a rotation shaft 102 provided on the rotation mechanism 101. And, the polishing instrument 104 which is rotated by the rotation mechanism 103 is brought into contact with the damaged portion D to effect polishing.
Also, apart from the polishing device S, which simply polishes the damaged portion D, there is a dust collecting type polishing device which performs polishing while collecting the dust (polishing chips, etc.) generated during polishing by a suction device provided at a predetermined position.
Here, a disc sander and a double action sander, which are generally used to remove paint and feather edges, will be described. In the disc sander, the rotation center of the rotation shaft 102 of the polishing device S is in alignment with that of the polishing instrument 104. The polishing instrument 104 rotates (revolves), as the rotation shaft 102 of the polishing device S rotates. On the other hand, in the double action sander, the rotation center of the polishing instrument 104 is offset from that of the rotation shaft 102, and the polishing instrument 104 rotates in eccentricity with respect to the polishing device S.
The polishing instrument 104 supported by the polishing device S is composed of a round holding plate 106 provided with an arbor 105 supported by the rotation shaft 102 of the polishing device S, and a polishing pad 107 which is secured to the lower side of the holding plate 106 and to the lower side of which a sand paper serving as the polishing member is detachably attached. As the rotation shaft 102 of the polishing device S rotates, the polishing pad 107 rotates. Note that, the holding plate 106 is a rigid member formed of a resin or the like, and the polishing pad 107 is formed of an elastic material such as a hard sponge.
When using this polishing device S, for example, as shown in FIG. 14, polishing is performed while holding the polishing device S by both hands in such a manner that the polishing instrument 104 is somewhat inclined with respect to the damaged portion D. That is, polishing is performed by using an end portion 108 of the polishing pad 104. Note that, polishing by using the end portion 108 of the polishing instrument 104 is performed because the contact area and the contact pressure of the polishing pad 104 with respect to the damaged portion D can be easily changed according to the polishing condition.
However, when a person who is not used to this type of polishing device uses the polishing device, excessive or uneven polishing can result. This is particularly true in the case of the process for removing coating films and feather edges, in which polishing is performed by using an end portion of the polishing instrument.
The reasons for this are as follows. Firstly, when performing polishing by using an end portion of the polishing instrument, the area by which the instrument is held in contact with the damaged portion is small, so that it is difficult for the user to adjust the pressure with which the polishing instrument is held in contact with the damaged portion. Secondly, since the polishing pad is formed of an elastic member, such as a hard sponge, any fluctuation in the contact pressure or any change in the contact angle will result in great deformation of the polishing pad, thereby impairing the stability of the polishing instrument with respect to the damaged portion.
In addition, according to the above-mentioned reasons, in the polishing using the conventional polishing instrument, the operating direction of the polishing device S with respect to the dent of the damaged portion D is limited. Specifically, as shown in FIG. 12, it is impossible to perform polishing while inclining the polishing instrument in the direction in which the polishing device S advances. This is because the pressurizing force applied to the polishing device acts on the end portion of the polishing instrument rotating at high speed to further increase the deformation amount of the polishing instrument, thereby impairing the stability of the instrument.
Thus, to obtain a satisfactory polished face by using the conventional polishing instrument, it takes a lot of skill and a careful operation.
Further, since the polishing pad is formed of an elastic material, such as a hard sponge, continuous polishing by using its end portion results in a local deterioration of the polishing pad, making it necessary to replace the polishing instrument at an early stage.
The present invention has been made in view of the above problems. It is an object of the present invention to provide a polishing instrument which is superior in operability and stability and which makes it possible to polish a surface into a desired shape by an easy operation. Another object of the present invention is to provide a polishing instrument which has a superior durability and which makes it possible to continuously perform polishing by using its end portion.
The polishing instrument of the present invention comprises: a rotatable rotary substrate portion equipped with a polishing plane holding a polishing material on its surface; a plurality of movable substrate portions equipped with polishing planes which hold the polishing material on their surfaces, which are provided in the peripheral edge of the rotary substrate portion, and which rotate about a connection line connecting them to the rotary substrate portion; and biasing means for biasing the polishing planes of the movable substrate portions toward a position where they are flush with the polishing plane of the rotary substrate portion.
In the polishing instrument of the present invention, the polishing plane is composed of a plurality of planes. When polishing is performed by using an end portion of the polishing instrument, the polishing planes provided in the movable substrate portions are brought into contact with the surface to be polished. That is, in the polishing instrument of the present invention, the portion corresponding to the end portion of the conventional polishing pad constitutes the movable substrate portions. Note that, the area of the polishing planes of the movable substrate portion is sufficiently smaller than that of the polishing plane of the entire polishing instrument.
Thus, when performing polishing by using the end portion, there is no great variation in the contact area of the polishing plane and the surface to be polished. Further, the pressure with which the polishing instrument is held in contact with the surface to be polished can be easily adjusted. Thus, an improvement is achieved in terms of the stability of the polishing instrument with respect to the surface to be polished, and it is possible, without any special skill, to polish the surface to be polished into a desired configuration by an easy operation.
Further, in the polishing instrument of the present invention, even if polishing is performed while inclining the polishing instrument toward the direction in which the polishing instrument advances, the polishing plane undergoes deformation while maintaining a predetermined configuration, so that the sense of stability is not impaired, making it possible to obtain a satisfactory polishing plane. Further, even if polishing is continuously performed by using the end portion of the polishing instrument, the polishing planes of the movable substrate portions of the polishing instrument are in contact with the surface to be polished, so that no undue stress is applied to the end portion of the polishing instrument, making it possible to restrain a deterioration in the end portion.
Further, in accordance with the present invention, there is provided a polishing instrument according to the first aspect of the invention further comprising a holding plate provided so as to be parallel to the rotary substrate portion and the movable substrate portions and at a predetermined distance therefrom, and elastic members provided between the holding plate and the movable substrate portions. The polishing planes of the movable substrate portions may be biased by the elasticity of the elastic members from the holding plate side toward a position where they are flush with the polishing plane of the rotary substrate portion.
In this construction, the biasing means is provided between the movable substrate portions and the holding plate so as to be erect. Thus, it is possible to directly apply an external force (pressurizing force) to the movable substrate portions to perform polishing. Therefore, a further improvement is achieved in terms of the stability of the polishing instrument with respect to the damaged portion. Further, apart from the provision of a biasing means, it is possible to absorb the slight vibration due to the contact between the polishing instrument and the damaged portion.
Further, in the polishing instrument of the present invention, the rotary substrate portion is circular, and the movable substrate portions can be provided at a plurality of positions at equal intervals in the circumference of the rotary substrate portion. In this construction, the connection line between the movable substrate portions and the rotary substrate portion runs in an arc, so that the bent portion extending from the rotary substrate portion to the movable substrate portions can be smoothly brought into contact with the dent inner surface of the damaged portion. Further, since the movable substrate portions are provided at a plurality of positions at equal intervals in the circumference of the rotary substrate portion, the contact (rotation) resistance as a result of the rotation of the polishing instrument with respect to the damaged portion is uniform over the entire circumference, thereby stabilizing the rotation of the polishing instrument.
Further, in the polishing instrument of the present invention, the outer end edges of the plurality of movable substrate portions can form one and the same curve. That is, in the condition in which the rotary substrate portion and the movable substrate portions are connected to each other, the outer end edges of the movable substrate portions form a continuous arc. Thus, the outer end edges of the movable substrate portions can be smoothly brought into contact with the dent inner surface of the damaged portion.
Further, in the polishing instrument of the present invention, the area of the polishing planes of the movable substrate portions can be smaller than the area of the polishing plane of the rotary substrate portion. In this construction, when performing polishing by using the entire polishing plane consisting of the rotary substrate portion and the movable substrate portion, the rotary substrate portion which makes little movement relative to the holding plate comes into contact with the surface to be polished in a large area. Thus, the polishing instrument is stable even when polishing is performed by using the entire polishing plane.
Further, in the polishing device of the present invention, the movable range for the movable substrate portions with respect to the rotary substrate portion can be determined to be between a position where the polishing planes of the movable substrate portions are flush with the polishing plane of the rotary substrate portion and a position where a part of the movable substrate portions is in contact with the side edge of the holding plate. By thus setting the movable range of the movable substrate portions beforehand, even a person who is not used to the operation of a polishing instrument, if he performs polishing within the movable range, can maintain the contact angle made by the damaged portion and the polishing instrument within an appropriate range.
Further, in the polishing instrument of the present invention, at least one elastic member may be provided for each of the plurality of movable substrate portions. By thus arbitrarily setting the number of elastic members provided in each movable substrate portion, it is possible to obtain movable substrate portions having a desired restoring force (elastic force). Further, since a biasing means is provided for each movable substrate portion, each movable substrate portion individually comes into contact with the damaged portion with a predetermined contact pressure. Thus, it is possible to perform polishing with higher accuracy by using the end portion of the polishing instrument.
Further, in the polishing instrument of the present invention, there may be provided a dust collecting passage extending through each of the polishing planes, the elastic members, and the holding plate. The dust collecting passage may be connected to a suction device using a negative pressure as the suction source. In this construction, the dust generated on the polishing plane can be guided to the suction device by utilizing the dust collecting passage. That is, it is possible to obtain a polishing instrument adapted to a dust collecting type polishing instrument.
As described above, the present invention provides a polishing instrument which is superior in operability and stability, making it possible to polish a surface into a desired configuration by an easy operation.
Further, since the portion corresponding to the end portion of the polishing instrument is formed of a plate of a resin or the like, a superior durability can be achieved. In addition, it comes into face contact with the surface to be polished, thereby improving the durability of the end portion. Thus, polishing can be continuously conducted by using the end portion of the polishing instrument. Further, local excessive wear of the sand paper can be restrained.
Further, in the polishing instrument of the present invention, even when performing polishing by using the end portion of the instrument, it can be brought into contact with the surface to be polished by a large contact area. Further, the operation of the polishing instrument requires no particularly careful handling. Thus, it is possible to remove old coating films in a short time.